The present invention relates to a speaker diaphragm edge such that an unprecedented new material is used and it is formed and finished precisely and correctly by means of a skillful processing method, and relates to its manufacturing method.
In brief, the structure of the general speaker shown in FIG. 1 is such that the speaker shown in the same figure is an electrodynamic-type speaker with a commonly known structure. 1 indicates the speaker proper. 2 is the magnetic circuit that contains magnet 2a and is held and attached to the base of the frame 7. 3 is the voice coil, which is suspended so as not to contact the magnetic domain wall within the toroidal magnetic gap 2b of the aforementioned magnetic circuit 2. Also, the tip center part of the truncated-conical diaphragm 5 is adhered and attached to the tip of the voice coil bobbin 3a. The damper 4 connects the tip center part of the diaphragm 5 and the frame 7. Also, the diaphragm edge 6 connects the periphery of the diaphragm 5 and the outer edge of the frame 7. Both the damper 4 and the diaphragm edge 6 are compliant in the direction of the principal axis of the speaker 1, and the diaphragm 5 and the voice coil 3 are held vibratably within the frame 7. When audio current flows in the voice coil 3, the aforementioned audio current and the magnetic flux within the toroidal magnetic gap 2b interlink and a driving force is generated, thereby vibrating the diaphragm 5, causing it to emit sound waves.
At its inner and outer peripheries, the diaphragm edge 6 is composed, respectively, of the inner attachment margin 6a that is adhered to the outer periphery of the diaphragm 5 and the outer attachment margin 6c that is adhered to the outer edge of the frame 7. Between them is formed the toroidal flexible part 6b that vibratably supports both the damper 4 and the diaphragm 5 and is compliant with respect to the displacement along the principal axis. In the speaker assembly process, the diaphragm 5, voice coil 3, damper 4, and edge 6 normally are manufactured as a single member, and the diaphragm 5 and diaphragm edge 6 are united by adhering the outer periphery of the diaphragm 5 and the inner attachment margin 6a of the diaphragm edge 6, in the preproduction process. The outer edge of the frame 7 and the outer attachment margin 6c of the diaphragm edge 6 are adhered in the speaker 1 assembly process.
Regarding the speaker diaphragm edge 6, whose shape is shown in FIG. 2, the diaphragm edge is conventionally made by impregnating the rolled base fabric 10 with a phenolic resin or a melaminic resin as the shaping agent, and the front and back are coated with a resonance inhibitor and a filler that prevents the leakage of air, and this is hot-pressed in a mold to form the specified shape. In some cases, the filler and resonance inhibitor are applied after the specified shape is formed. In a conventional diaphragm edge 6 with such a structure, the entire base fabric is impregnated with a shaping agent, so a large quantity of the aforementioned shaping agent is required. The punching slugs after punching to the final shape contain the shaping agent, so there are problems with the cost and trouble of disposal. Also, phenolic resin and melaminic resin are thermosetting resins and are very hard after molding, so it is necessary to dilute the concentration of impregnated resin solution, to obtain the flexibility required by the edge. Therefore, its strength is inadequate, so the life of its preferred state is short. Another drawback is that the speaker performance deteriorates as a result of the nonuniformity of the applied film and the impregnation state.